Objectives of our longitudinal research are to: 1) identify high risk factors associated with the occurrence of specific types of depression within household aggregates, and 2) determine relationships between dimensions of family functioning and depression. After a 1-year pilot study of 50 families, members of a systematic random sample of 300 household aggregates in the Louisville SMSA (ca. 1000 adults and children) will be interviewed at 6-month intervals for 4 years. We shall: 1) screen and diagnose (DIS/DICA) adults and children for specific types of depression in each interview; 2) collect data about risk factors at 3 levels -- individual, familial, and socioenvironmental; 3) evaluate over time, the interactions among stressful life events, dimensions of family functioning and depression within household aggregates to establish sequences, associations, and impacts; and 4) conduct blood studies of every third family to determine associations among biological factors (e.g., degree of genetic closeness within and across families), risk factors, and depression, and also to construct a biochemical "fingerprint" of each member while monitoring drugs and toxins. The fingerprint will verify independently (orthogonally) associations obtained from other data analyses. The study of risk factors will emphasize, but not be limited to, those at the interpersonal or familial level to fill the gap in knowledge of risk factors between the individual and environmental levels. We shall analyze the data longitudinally by use of increment-decrement life table, path analytic, and log linear techniques. The significance is that: 1) prospective analyses of individuals and families permit an assessment of incidence, duration, and outcome of specific depressive disorders; 2) the prospective design enables us to assess in children and adults the etiologic importance of interactive risk factors in the affective disorders; 3) few epidemiologic studies of affective disorders have focused on family functioning; and 4) the findings should contribute to knowledge about the etiology of depressions and to family theory.